摘要:
以福建省罗源县正在建设的龟屿隧道爆破工程为例,分析了隧道爆破地震波的传播规律和对毗邻
大黄鱼育苗池的水中声场环境的影响。研究结果表明:(1)爆破作业将显著地增加毗邻大黄鱼育苗池的水中
声强(比未爆破前的水中声强高约60~80dB),强度的增加与爆破药量成正比,与爆点的距离成反比,且距离
的影响远大于爆破药量的影响;(2)在海水高潮和低潮的2个时段,由于爆破地震波传播途径的不同,毗邻大
黄鱼育苗池的水中声场环境在强度和频率能量分布上均存在差异:育苗池中低潮时段的水中声强小于高潮
时段的水中声强;低潮时段声波能量主要分布在小于400Hz的较低频带上,而高潮时段的声波能量主要分布
在200~1000Hz的较高频带上。因此,为减小隧道爆破对育苗池中大黄鱼的伤害,结合分析大黄鱼对水中
声波的敏感频率(500~800Hz)及敏感强度,需降低育苗池的水中声强并使声波能量分布向低频带转移,选
择在低潮时段、采用低药量进行隧道作业。
Abstract:
Underwatersoundeffectsgeneratedbytunnel-explosionwerestudiedandanobservation
wasperformedtomonitortheunderwatersoundpressureinPseudosciaenacroceasbreedingpond
whenGuiyutunnelblastengineeringoccurredthithercoastalharborinLuoyuanCounty,FujianProvince.
Basedonacoustictheoryoftransmissionandreflectiononsolid-fluidinterface,theresultsshow
thatblastingseismicwave makesimpactonunderwaterenvironmentthroughtwokindsofsound
transmittedpaths.Theunderwatersoundintensityincreasessharply(upto150dB)inbreedingpond
whenGuiyutunnelblastengineeringoccurs,andtheincrementofsoundintensityisdirectlyproportionaltothemassofexplosivesaswellaswhichisinverselyproportionaltothedistancefro
blasting
point.However,theeffectofdistanceisgreaterthanthatofmass.Additionally,atdifferenttimeof
lowtideandhightide,thesoundintensitygeneratedbyblastingseismicwaveinpondhasasignificant
differenceduetothetwopathsofsoundpropagationindifferenttransmittedmedia.Withtheincrementofdistance,
soundintensityatlowtidetimedeclinesmorequicklythanthatathightidetime.
Similarly,thesoundenergydistributioninfrequencybandhasdifferentshape.Soundathightide
timeisdominantinfrequencybandof200~1000Hz.Ontheotherhand,thefrequencyofsoundin
pondatlowtidetimeismainlylessthan400Hz.Thegreaterofthewaterdepthaboveseabedis,the
lowerofthecut-offlowfrequencyisforunderwateracousticwaveguideeffect.Consequently,thelow
tidetimeforGuiyutunnelblastingshouldbechosensothatitcandecreasetheharmofhighintensity
inPseudosciaenacroceasbreedingpond,avoidingtodoharmtopseudosciaenacroceasbodyinthe
soundresonantfrequencyof500~800Hz.
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